package com.youhome.service.utils;

/**
 * Created by yuliang on 2015/3/20.
 */
public class LocationUtils {
    private static double EARTH_RADIUS = 6378.137;

    private static double rad(double d) {
        return d * Math.PI / 180.0;
    }

    /**
     * 通过经纬度获取距离(单位：米)
     * @param lat1
     * @param lng1
     * @param lat2
     * @param lng2
     * @return
     */
    public static double getDistance(double lat1, double lng1, double lat2,
                                     double lng2) {
        double radLat1 = rad(lat1);
        double radLat2 = rad(lat2);
        double a = radLat1 - radLat2;
        double b = rad(lng1) - rad(lng2);
        double s = 2 * Math.asin(Math.sqrt(Math.pow(Math.sin(a / 2), 2)
                + Math.cos(radLat1) * Math.cos(radLat2)
                * Math.pow(Math.sin(b / 2), 2)));
        s = s * EARTH_RADIUS;
        s = Math.round(s * 10000d) / 10000d;
        s = s*1000;
        return s;
    }

//    public static void main(String[] args) {
//        //40.7520027161 lng:-74.002166748 lat1:40.751812 lng1:-74.00182
////        16689.6米
////        39.0米
//        System.out.println(getDistance(29.490295,106.486654,29.615467,106.581515)+"米");
//        System.out.println(getDistance(-74.002166748,40.7520027161,-74.00182,40.751812)+"米");
//    }
}
